A variety of different printing processes for use in printing presses are known. One such printing process is inkjet printing or ink-jet printing. In this process, individual droplets of printing ink are ejected through nozzles of print heads and are transferred to a printing material so as to produce a printed image on the printing material. By actuating a plurality of nozzles individually, different printed images can be produced. Since no fixed printing forme is involved, each printed product can be produced individually. This allows personalized printed products to be produced, and/or, since printing forms are dispensed with, allows small print runs of printed products to be produced at low cost.
The precise alignment of printed images on the front and back sides of a printing material that is imprinted on both sides is referred to as register (DIN 16500-2). In multicolor printing, the merging and precise correlation of individual printed images of different colors to form a single image is referred to as color-to-color registration (DIN 16500-2). Suitable measures are necessary in inkjet printing in order to maintain color-to-color registration and/or register.
EP 2 202 081 A1 and JP 2003-063707 A each disclose a printing press which has a first printing unit and a dryer, the first printing unit comprising a central cylinder with a separate drive motor assigned to the first central cylinder and at least one inkjet print head.
U.S. Pat. No. 5,566,616 A discloses a printing press comprising a rotatable central cylinder, inkjet print heads, a cooling unit and a dryer, which operates using either temperature and air flow or radiation-induced curing.
U.S. Pat. No. 6,053,107 A discloses a printing press which has a driven central cylinder and a dryer with a cooling unit.
DE 10 2011 076 899 A1 discloses a printing press which has at least one printing unit and at least one print head embodied as an inkjet print head.
DE 10 2010 001 146 A1 and DE 43 18 299 A1 each disclose a threading means for threading web-type printing material into a printing press. EP 1 197 329 A1 discloses a threading tip that can interact with a threading belt or a threading chain. US 2011/0043554 A1 discloses a printing press in which at least one printing material guiding element is moved away from at least one print head in order to thread in a material web.
DE 10 2004 017 801 A1, US 2005/0024421 A1, DE 10 201 0 037 829 A1, JP 2004 268 511 A, US 2006/0119646 A1, U.S. Pat. No. 5,206,666 A, U.S. Pat. No. 5,757,399 A and U.S. Pat. No. 7,455,401 B2 each disclose a printing press comprising print heads and a maintenance device that can be moved along an actuating path. US 2011/0149004 A1 discloses a printing press having print heads that can be moved along an actuating path. U.S. Pat. No. 8,262,198 B2 discloses a printing press with adjustable print heads. DE 23 49 453 A1 discloses movable nozzles of a liquid jet recorder.
US 2009/0284566 A1 discloses a printing press in which four positioning devices can be used to move print heads in different linear directions to ensure positioning accuracy, and said print heads can be transported to a stationary maintenance device by moving parallel to a rotational axis of a printing material guiding element.
DE 10 2005 060 786 A1, EP 2 127 885 A1 and US 2008/0273063 A1 each disclose a printing press which has at least one system for supplying coating medium and at least two inkjet print heads, each of which is connected via a fluid line to a main reservoir, the main reservoir being connected via a supply line and a drain line to an intermediate reservoir.